Kickdown / 3rd Gear

[nachum kadmiel]

I have a 69 automatic 280sl. I have two (maybe related and maybe not) problems:
1. The Kickdown doesn't work at all.
2. The 3rd gear engages very late - only at about 400rpms.

Any ideas?

Thanks in advance for all the experts.

[rwmastel]

Nachum,

Hi.  You're a full member, so you could start with https://www.sl113.org/wiki/Automatic/Start.  Lots to read there and become educated on, specially if you plan to perform work yourself.  Will you be doing the work, or will a mechanic/shop do the work?

Also, search the forums for "no kickdown" (using the quotes) and you should find good discussions to read.

This is our New Member Introductions thread, if you care to officially introduce yourself.  https://www.sl113.org/forums/index.php?topic=529.1500

Looks like you have had transmission shift issues for some time.  https://www.sl113.org/forums/index.php?topic=28666.0

[teahead]

Ya, I messed w/the pressure on the modulator hoping to get it to shift a little later.

Now I screwed something up and kickdown no longer works.

I'm assuming you mean 4000RPM for the 2-3 upshift?  Or the 3-4 upshift?  or both?

[Cees Klumper]

On the kickdown, start by looking at whether the gas pedal manages to depress the switch that is supposed to effectuate the kick-down (if vacuum/speed/RPM etc don't accomplish that). If the switch is pressed, check whether it's working, with a test light or what have you, and check the wiring from/to the switch. Don't know if the circuit is on a fuse with other things (likely so) so if those other things are working, it's probably not the fuse.

[nachum kadmiel]

After checking things up - my problem is the final gear (3-4) engages in 4000rpm+. I have tried changing the gear membrane screw, all the way out, with no success. Amy more ideas?

[nachum kadmiel]

Update: Kickdown was fixed.

By the literature the modulator rod is supposed to go down when the ignition is turned on. However, it does not move at all. As the Kickdown is working - it seems to me that the solenoid is working. Any ideas?

Nachum

[ja17]

If you lower the modulator pressure too much the kickdown will stop working. The linkage rod and the three position solenoid must be in the rear position, when the engine linkage is at rest and ignition on.  It must move to center after the accelerator pedal and linkage is slightly depressed. At full throttle when the pedal depresses the kickdown switch on the floor, the transmission linkage and solenoid should move to forward position. The turnbuckle on the transmission linkage is also adjustable to change the length of the linkage rod which also effects the modulator pressure. It must be kept in a certain range of it's adjustable length, in order for it to be able to move to all three positions. You must first make sure the venturi switch is adjusted correctly and is functioning. You must also make sure your transmission linkage and three position solenoid can move freely. You may have to check and set your modulator pressure, and kickdown pressure with a gauge if you are lost. The website for "Sun Valley Transmissions" has an excellent step by step procedure to set and adjust these "16 bolt oil pan" transmissions. Lastly when everything is adjusted properly and the problem still persists, there can be an issue with the rear governor assembly which will cause a late shifting situation. Search for problems with "automatic late shifting" and "automatic transmission rear governor"

[nachum kadmiel]

Hello friends/
Thnks for your advice and help.
nachum